This invention relates to metallic laminates, more particularly those in which the metallic layers are bonded by a thermoplastic adhesive.
It is known to make a laminate (hereinafter called a laminate of the type described) comprising sheet metal, such as galvanized sheet steel, and aluminium foil, with an interposed thermoplastic adhesive which, under the application of heat and pressure, adheres to the foil and sheet metal. The laminated product may be roll-formed to desired profile for roofing or wall cladding and, when erected on structures with the aluminium foil facing inwards, it has good heat insulating properties because of the low emission of radiant heat from the aluminium foil surface. The thermoplastic adhesive employed may be polyethylene, with or without additives, and hereinafter called "polythene".
A laminate of the type described may have metallic foil likewise adhered to the second side of the sheet metal so that, when used in a structure, this second metal foil layer faces outwards, for improved weathering, appearance and/or reflection of heat, and this second layer of foil may be of aluminium or any other suitable metal.
A difficulty in the manufacture of a laminate of the type described is in obtaining a sufficiently good bond strength within the laminate to enable roll-forming to be carried out satisfactorily and to minimise subsequent damage in the handling and application of the laminate.